They used to match lipsticks and nail polishes. Allthough I cannot recall ever seeing the nail polish in Grid, the old LS in Grid was a steel grey, so my guess is that Grid NP is that same colour.
I used to have Grid nail polish, it was a good few years ago though. If my memorary serves me well, I think it is a purple/grey colour. I know I was heavily into purple nail polishes at that time. I saw one eBay a couple o months ago.
I discovered a new bottle of MAC "Grid" this week. I used it today and love it. It is a medium shade of gray, with a faint undertone of purple and a slight metallic-like finish